Data compression, whether lossy or lossless, often uses entropy coding to encode a decorrelated signal as a sequence of bits, i.e. a bitstream. Efficient data compression has a wide range of applications, such as data, image, audio, and video encoding. By way of example, ITU-T H.264/MPEG AVC is a video coding standard widely used for encoding/decoding video. It defines a number of different profiles for different applications, including the Main profile, Baseline profile and others.
There are a number of standards for encoding/decoding images and videos, including H.264, that employ lossy compression processes to produce binary data. For example, H.264 includes a prediction operation to obtain residual data, followed by a DCT transform and quantization of the DCT coefficients. The resulting data, including quantized coefficients, motion vectors, coding mode, and other related data, is then entropy coded to generate a bitstream of data for transmission or storage on a computer-readable medium.
A number of coding schemes have been developed to encode binary data. For example, JPEG images may be encoded using Huffman codes. The H.264 standard allows for two possible entropy coding processes: Context Adaptive Variable Length Coding (CAVLC) or Context Adaptive Binary Arithmetic Coding (CABAC). CABAC results in greater compression than CAVLC, but CABAC is more computationally demanding.
An entropy encoder/decoder is a component within a compression encoder/decoder. While the entropy encoder/decoder component is only a small portion of the overall compression encoder/decoder, it can present a significant bottleneck in real-time compression because of the serial nature of its operation.
It would be advantageous to provide for an improved implementation of an entropy decoder.
Similar reference numerals may have been used in different figures to denote similar components.